/*========================================================================= Program: KWSys - Kitware System Library Module: $RCSfile: RegularExpression.cxx,v $ Copyright (c) Kitware, Inc., Insight Consortium. All rights reserved. See Copyright.txt or http://www.kitware.com/Copyright.htm for details. This software is distributed WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the above copyright notices for more information. =========================================================================*/ // // Copyright (C) 1991 Texas Instruments Incorporated. // // Permission is granted to any individual or institution to use, copy, modify // and distribute this software, provided that this complete copyright and // permission notice is maintained, intact, in all copies and supporting // documentation. // // Texas Instruments Incorporated provides this software "as is" without // express or implied warranty. // // // Created: MNF 06/13/89 Initial Design and Implementation // Updated: LGO 08/09/89 Inherit from Generic // Updated: MBN 09/07/89 Added conditional exception handling // Updated: MBN 12/15/89 Sprinkled "const" qualifiers all over the place! // Updated: DLS 03/22/91 New lite version // #include "kwsysPrivate.h" #include KWSYS_HEADER(RegularExpression.hxx) // Work-around CMake dependency scanning limitation. This must // duplicate the above list of headers. #if 0 # include "RegularExpression.hxx.in" #endif #include #include namespace KWSYS_NAMESPACE { // RegularExpression -- Copies the given regular expression. RegularExpression::RegularExpression (const RegularExpression& rxp) { if ( !rxp.program ) { this->program = 0; return; } int ind; this->progsize = rxp.progsize; // Copy regular expression size this->program = new char[this->progsize]; // Allocate storage for(ind=this->progsize; ind-- != 0;) // Copy regular expresion this->program[ind] = rxp.program[ind]; this->startp[0] = rxp.startp[0]; // Copy pointers into last this->endp[0] = rxp.endp[0]; // Successful "find" operation this->regmust = rxp.regmust; // Copy field if (rxp.regmust != 0) { char* dum = rxp.program; ind = 0; while (dum != rxp.regmust) { ++dum; ++ind; } this->regmust = this->program + ind; } this->regstart = rxp.regstart; // Copy starting index this->reganch = rxp.reganch; // Copy remaining private data this->regmlen = rxp.regmlen; // Copy remaining private data } // operator= -- Copies the given regular expression. RegularExpression& RegularExpression::operator= (const RegularExpression& rxp) { if(this == &rxp) { return *this; } if ( !rxp.program ) { this->program = 0; return *this; } int ind; this->progsize = rxp.progsize; // Copy regular expression size delete [] this->program; this->program = new char[this->progsize]; // Allocate storage for(ind=this->progsize; ind-- != 0;) // Copy regular expresion this->program[ind] = rxp.program[ind]; this->startp[0] = rxp.startp[0]; // Copy pointers into last this->endp[0] = rxp.endp[0]; // Successful "find" operation this->regmust = rxp.regmust; // Copy field if (rxp.regmust != 0) { char* dum = rxp.program; ind = 0; while (dum != rxp.regmust) { ++dum; ++ind; } this->regmust = this->program + ind; } this->regstart = rxp.regstart; // Copy starting index this->reganch = rxp.reganch; // Copy remaining private data this->regmlen = rxp.regmlen; // Copy remaining private data return *this; } // operator== -- Returns true if two regular expressions have the same // compiled program for pattern matching. bool RegularExpression::operator== (const RegularExpression& rxp) const { if (this != &rxp) { // Same address? int ind = this->progsize; // Get regular expression size if (ind != rxp.progsize) // If different size regexp return false; // Return failure while(ind-- != 0) // Else while still characters if(this->program[ind] != rxp.program[ind]) // If regexp are different return false; // Return failure } return true; // Else same, return success } // deep_equal -- Returns true if have the same compiled regular expressions // and the same start and end pointers. bool RegularExpression::deep_equal (const RegularExpression& rxp) const { int ind = this->progsize; // Get regular expression size if (ind != rxp.progsize) // If different size regexp return false; // Return failure while(ind-- != 0) // Else while still characters if(this->program[ind] != rxp.program[ind]) // If regexp are different return false; // Return failure return (this->startp[0] == rxp.startp[0] && // Else if same start/end ptrs, this->endp[0] == rxp.endp[0]); // Return true } // The remaining code in this file is derived from the regular expression code // whose copyright statement appears below. It has been changed to work // with the class concepts of C++ and COOL. /* * compile and find * * Copyright (c) 1986 by University of Toronto. * Written by Henry Spencer. Not derived from licensed software. * * Permission is granted to anyone to use this software for any * purpose on any computer system, and to redistribute it freely, * subject to the following restrictions: * * 1. The author is not responsible for the consequences of use of * this software, no matter how awful, even if they arise * from defects in it. * * 2. The origin of this software must not be misrepresented, either * by explicit claim or by omission. * * 3. Altered versions must be plainly marked as such, and must not * be misrepresented as being the original software. * * Beware that some of this code is subtly aware of the way operator * precedence is structured in regular expressions. Serious changes in * regular-expression syntax might require a total rethink. */ /* * The "internal use only" fields in regexp.h are present to pass info from * compile to execute that permits the execute phase to run lots faster on * simple cases. They are: * * regstart char that must begin a match; '\0' if none obvious * reganch is the match anchored (at beginning-of-line only)? * regmust string (pointer into program) that match must include, or NULL * regmlen length of regmust string * * Regstart and reganch permit very fast decisions on suitable starting points * for a match, cutting down the work a lot. Regmust permits fast rejection * of lines that cannot possibly match. The regmust tests are costly enough * that compile() supplies a regmust only if the r.e. contains something * potentially expensive (at present, the only such thing detected is * or + * at the start of the r.e., which can involve a lot of backup). Regmlen is * supplied because the test in find() needs it and compile() is computing * it anyway. */ /* * Structure for regexp "program". This is essentially a linear encoding * of a nondeterministic finite-state machine (aka syntax charts or * "railroad normal form" in parsing technology). Each node is an opcode * plus a "next" pointer, possibly plus an operand. "Next" pointers of * all nodes except BRANCH implement concatenation; a "next" pointer with * a BRANCH on both ends of it is connecting two alternatives. (Here we * have one of the subtle syntax dependencies: an individual BRANCH (as * opposed to a collection of them) is never concatenated with anything * because of operator precedence.) The operand of some types of node is * a literal string; for others, it is a node leading into a sub-FSM. In * particular, the operand of a BRANCH node is the first node of the branch. * (NB this is *not* a tree structure: the tail of the branch connects * to the thing following the set of BRANCHes.) The opcodes are: */ // definition number opnd? meaning #define END 0 // no End of program. #define BOL 1 // no Match "" at beginning of line. #define EOL 2 // no Match "" at end of line. #define ANY 3 // no Match any one character. #define ANYOF 4 // str Match any character in this string. #define ANYBUT 5 // str Match any character not in this // string. #define BRANCH 6 // node Match this alternative, or the // next... #define BACK 7 // no Match "", "next" ptr points backward. #define EXACTLY 8 // str Match this string. #define NOTHING 9 // no Match empty string. #define STAR 10 // node Match this (simple) thing 0 or more // times. #define PLUS 11 // node Match this (simple) thing 1 or more // times. #define OPEN 20 // no Mark this point in input as start of // #n. // OPEN+1 is number 1, etc. #define CLOSE 30 // no Analogous to OPEN. /* * Opcode notes: * * BRANCH The set of branches constituting a single choice are hooked * together with their "next" pointers, since precedence prevents * anything being concatenated to any individual branch. The * "next" pointer of the last BRANCH in a choice points to the * thing following the whole choice. This is also where the * final "next" pointer of each individual branch points; each * branch starts with the operand node of a BRANCH node. * * BACK Normal "next" pointers all implicitly point forward; BACK * exists to make loop structures possible. * * STAR,PLUS '?', and complex '*' and '+', are implemented as circular * BRANCH structures using BACK. Simple cases (one character * per match) are implemented with STAR and PLUS for speed * and to minimize recursive plunges. * * OPEN,CLOSE ...are numbered at compile time. */ /* * A node is one char of opcode followed by two chars of "next" pointer. * "Next" pointers are stored as two 8-bit pieces, high order first. The * value is a positive offset from the opcode of the node containing it. * An operand, if any, simply follows the node. (Note that much of the * code generation knows about this implicit relationship.) * * Using two bytes for the "next" pointer is vast overkill for most things, * but allows patterns to get big without disasters. */ #define OP(p) (*(p)) #define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377)) #define OPERAND(p) ((p) + 3) const unsigned char MAGIC = 0234; /* * Utility definitions. */ #define UCHARAT(p) ((const unsigned char*)(p))[0] #define FAIL(m) { regerror(m); return(0); } #define ISMULT(c) ((c) == '*' || (c) == '+' || (c) == '?') #define META "^$.[()|?+*\\" /* * Flags to be passed up and down. */ #define HASWIDTH 01 // Known never to match null string. #define SIMPLE 02 // Simple enough to be STAR/PLUS operand. #define SPSTART 04 // Starts with * or +. #define WORST 0 // Worst case. ///////////////////////////////////////////////////////////////////////// // // COMPILE AND ASSOCIATED FUNCTIONS // ///////////////////////////////////////////////////////////////////////// /* * Global work variables for compile(). */ static const char* regparse; // Input-scan pointer. static int regnpar; // () count. static char regdummy; static char* regcode; // Code-emit pointer; ®dummy = don't. static long regsize; // Code size. /* * Forward declarations for compile()'s friends. */ // #ifndef static // #define static static // #endif static char* reg (int, int*); static char* regbranch (int*); static char* regpiece (int*); static char* regatom (int*); static char* regnode (char); static const char* regnext (register const char*); static char* regnext (register char*); static void regc (unsigned char); static void reginsert (char, char*); static void regtail (char*, const char*); static void regoptail (char*, const char*); #ifdef STRCSPN static int strcspn (); #endif /* * We can't allocate space until we know how big the compiled form will be, * but we can't compile it (and thus know how big it is) until we've got a * place to put the code. So we cheat: we compile it twice, once with code * generation turned off and size counting turned on, and once "for real". * This also means that we don't allocate space until we are sure that the * thing really will compile successfully, and we never have to move the * code and thus invalidate pointers into it. (Note that it has to be in * one piece because free() must be able to free it all.) * * Beware that the optimization-preparation code in here knows about some * of the structure of the compiled regexp. */ // compile -- compile a regular expression into internal code // for later pattern matching. bool RegularExpression::compile (const char* exp) { register const char* scan; register const char* longest; register unsigned long len; int flags; if (exp == 0) { //RAISE Error, SYM(RegularExpression), SYM(No_Expr), printf ("RegularExpression::compile(): No expression supplied.\n"); return false; } // First pass: determine size, legality. regparse = exp; regnpar = 1; regsize = 0L; regcode = ®dummy; regc(MAGIC); if(!reg(0, &flags)) { printf ("RegularExpression::compile(): Error in compile.\n"); return false; } this->startp[0] = this->endp[0] = this->searchstring = 0; // Small enough for pointer-storage convention? if (regsize >= 32767L) { // Probably could be 65535L. //RAISE Error, SYM(RegularExpression), SYM(Expr_Too_Big), printf ("RegularExpression::compile(): Expression too big.\n"); return false; } // Allocate space. //#ifndef WIN32 if (this->program != 0) delete [] this->program; //#endif this->program = new char[regsize]; this->progsize = static_cast(regsize); if (this->program == 0) { //RAISE Error, SYM(RegularExpression), SYM(Out_Of_Memory), printf ("RegularExpression::compile(): Out of memory.\n"); return false; } // Second pass: emit code. regparse = exp; regnpar = 1; regcode = this->program; regc(MAGIC); reg(0, &flags); // Dig out information for optimizations. this->regstart = '\0'; // Worst-case defaults. this->reganch = 0; this->regmust = 0; this->regmlen = 0; scan = this->program + 1; // First BRANCH. if (OP(regnext(scan)) == END) { // Only one top-level choice. scan = OPERAND(scan); // Starting-point info. if (OP(scan) == EXACTLY) this->regstart = *OPERAND(scan); else if (OP(scan) == BOL) this->reganch++; // // If there's something expensive in the r.e., find the longest // literal string that must appear and make it the regmust. Resolve // ties in favor of later strings, since the regstart check works // with the beginning of the r.e. and avoiding duplication // strengthens checking. Not a strong reason, but sufficient in the // absence of others. // if (flags & SPSTART) { longest = 0; len = 0; for (; scan != 0; scan = regnext(scan)) if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) { longest = OPERAND(scan); len = int(strlen(OPERAND(scan))); } this->regmust = longest; this->regmlen = len; } } return true; } /* - reg - regular expression, i.e. main body or parenthesized thing * * Caller must absorb opening parenthesis. * * Combining parenthesis handling with the base level of regular expression * is a trifle forced, but the need to tie the tails of the branches to what * follows makes it hard to avoid. */ static char* reg (int paren, int *flagp) { register char* ret; register char* br; register char* ender; register int parno =0; int flags; *flagp = HASWIDTH; // Tentatively. // Make an OPEN node, if parenthesized. if (paren) { if (regnpar >= RegularExpression::NSUBEXP) { //RAISE Error, SYM(RegularExpression), SYM(Too_Many_Parens), printf ("RegularExpression::compile(): Too many parentheses.\n"); return 0; } parno = regnpar; regnpar++; ret = regnode(static_cast(OPEN + parno)); } else ret = 0; // Pick up the branches, linking them together. br = regbranch(&flags); if (br == 0) return (0); if (ret != 0) regtail(ret, br); // OPEN -> first. else ret = br; if (!(flags & HASWIDTH)) *flagp &= ~HASWIDTH; *flagp |= flags & SPSTART; while (*regparse == '|') { regparse++; br = regbranch(&flags); if (br == 0) return (0); regtail(ret, br); // BRANCH -> BRANCH. if (!(flags & HASWIDTH)) *flagp &= ~HASWIDTH; *flagp |= flags & SPSTART; } // Make a closing node, and hook it on the end. ender = regnode(static_cast((paren) ? CLOSE + parno : END)); regtail(ret, ender); // Hook the tails of the branches to the closing node. for (br = ret; br != 0; br = regnext(br)) regoptail(br, ender); // Check for proper termination. if (paren && *regparse++ != ')') { //RAISE Error, SYM(RegularExpression), SYM(Unmatched_Parens), printf ("RegularExpression::compile(): Unmatched parentheses.\n"); return 0; } else if (!paren && *regparse != '\0') { if (*regparse == ')') { //RAISE Error, SYM(RegularExpression), SYM(Unmatched_Parens), printf ("RegularExpression::compile(): Unmatched parentheses.\n"); return 0; } else { //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::compile(): Internal error.\n"); return 0; } // NOTREACHED } return (ret); } /* - regbranch - one alternative of an | operator * * Implements the concatenation operator. */ static char* regbranch (int *flagp) { register char* ret; register char* chain; register char* latest; int flags; *flagp = WORST; // Tentatively. ret = regnode(BRANCH); chain = 0; while (*regparse != '\0' && *regparse != '|' && *regparse != ')') { latest = regpiece(&flags); if (latest == 0) return (0); *flagp |= flags & HASWIDTH; if (chain == 0) // First piece. *flagp |= flags & SPSTART; else regtail(chain, latest); chain = latest; } if (chain == 0) // Loop ran zero times. regnode(NOTHING); return (ret); } /* - regpiece - something followed by possible [*+?] * * Note that the branching code sequences used for ? and the general cases * of * and + are somewhat optimized: they use the same NOTHING node as * both the endmarker for their branch list and the body of the last branch. * It might seem that this node could be dispensed with entirely, but the * endmarker role is not redundant. */ static char* regpiece (int *flagp) { register char* ret; register char op; register char* next; int flags; ret = regatom(&flags); if (ret == 0) return (0); op = *regparse; if (!ISMULT(op)) { *flagp = flags; return (ret); } if (!(flags & HASWIDTH) && op != '?') { //RAISE Error, SYM(RegularExpression), SYM(Empty_Operand), printf ("RegularExpression::compile() : *+ operand could be empty.\n"); return 0; } *flagp = (op != '+') ? (WORST | SPSTART) : (WORST | HASWIDTH); if (op == '*' && (flags & SIMPLE)) reginsert(STAR, ret); else if (op == '*') { // Emit x* as (x&|), where & means "self". reginsert(BRANCH, ret); // Either x regoptail(ret, regnode(BACK)); // and loop regoptail(ret, ret); // back regtail(ret, regnode(BRANCH)); // or regtail(ret, regnode(NOTHING)); // null. } else if (op == '+' && (flags & SIMPLE)) reginsert(PLUS, ret); else if (op == '+') { // Emit x+ as x(&|), where & means "self". next = regnode(BRANCH); // Either regtail(ret, next); regtail(regnode(BACK), ret); // loop back regtail(next, regnode(BRANCH)); // or regtail(ret, regnode(NOTHING)); // null. } else if (op == '?') { // Emit x? as (x|) reginsert(BRANCH, ret); // Either x regtail(ret, regnode(BRANCH)); // or next = regnode(NOTHING);// null. regtail(ret, next); regoptail(ret, next); } regparse++; if (ISMULT(*regparse)) { //RAISE Error, SYM(RegularExpression), SYM(Nested_Operand), printf ("RegularExpression::compile(): Nested *?+.\n"); return 0; } return (ret); } /* - regatom - the lowest level * * Optimization: gobbles an entire sequence of ordinary characters so that * it can turn them into a single node, which is smaller to store and * faster to run. Backslashed characters are exceptions, each becoming a * separate node; the code is simpler that way and it's not worth fixing. */ static char* regatom (int *flagp) { register char* ret; int flags; *flagp = WORST; // Tentatively. switch (*regparse++) { case '^': ret = regnode(BOL); break; case '$': ret = regnode(EOL); break; case '.': ret = regnode(ANY); *flagp |= HASWIDTH | SIMPLE; break; case '[':{ register int rxpclass; register int rxpclassend; if (*regparse == '^') { // Complement of range. ret = regnode(ANYBUT); regparse++; } else ret = regnode(ANYOF); if (*regparse == ']' || *regparse == '-') regc(*regparse++); while (*regparse != '\0' && *regparse != ']') { if (*regparse == '-') { regparse++; if (*regparse == ']' || *regparse == '\0') regc('-'); else { rxpclass = UCHARAT(regparse - 2) + 1; rxpclassend = UCHARAT(regparse); if (rxpclass > rxpclassend + 1) { //RAISE Error, SYM(RegularExpression), SYM(Invalid_Range), printf ("RegularExpression::compile(): Invalid range in [].\n"); return 0; } for (; rxpclass <= rxpclassend; rxpclass++) regc(static_cast(rxpclass)); regparse++; } } else regc(*regparse++); } regc('\0'); if (*regparse != ']') { //RAISE Error, SYM(RegularExpression), SYM(Unmatched_Bracket), printf ("RegularExpression::compile(): Unmatched [].\n"); return 0; } regparse++; *flagp |= HASWIDTH | SIMPLE; } break; case '(': ret = reg(1, &flags); if (ret == 0) return (0); *flagp |= flags & (HASWIDTH | SPSTART); break; case '\0': case '|': case ')': //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::compile(): Internal error.\n"); // Never here return 0; case '?': case '+': case '*': //RAISE Error, SYM(RegularExpression), SYM(No_Operand), printf ("RegularExpression::compile(): ?+* follows nothing.\n"); return 0; case '\\': if (*regparse == '\0') { //RAISE Error, SYM(RegularExpression), SYM(Trailing_Backslash), printf ("RegularExpression::compile(): Trailing backslash.\n"); return 0; } ret = regnode(EXACTLY); regc(*regparse++); regc('\0'); *flagp |= HASWIDTH | SIMPLE; break; default:{ register int len; register char ender; regparse--; len = int(strcspn(regparse, META)); if (len <= 0) { //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::compile(): Internal error.\n"); return 0; } ender = *(regparse + len); if (len > 1 && ISMULT(ender)) len--; // Back off clear of ?+* operand. *flagp |= HASWIDTH; if (len == 1) *flagp |= SIMPLE; ret = regnode(EXACTLY); while (len > 0) { regc(*regparse++); len--; } regc('\0'); } break; } return (ret); } /* - regnode - emit a node Location. */ static char* regnode (char op) { register char* ret; register char* ptr; ret = regcode; if (ret == ®dummy) { regsize += 3; return (ret); } ptr = ret; *ptr++ = op; *ptr++ = '\0'; // Null "next" pointer. *ptr++ = '\0'; regcode = ptr; return (ret); } /* - regc - emit (if appropriate) a byte of code */ static void regc (unsigned char b) { if (regcode != ®dummy) *regcode++ = b; else regsize++; } /* - reginsert - insert an operator in front of already-emitted operand * * Means relocating the operand. */ static void reginsert (char op, char* opnd) { register char* src; register char* dst; register char* place; if (regcode == ®dummy) { regsize += 3; return; } src = regcode; regcode += 3; dst = regcode; while (src > opnd) *--dst = *--src; place = opnd; // Op node, where operand used to be. *place++ = op; *place++ = '\0'; *place = '\0'; } /* - regtail - set the next-pointer at the end of a node chain */ static void regtail (char* p, const char* val) { register char* scan; register char* temp; register int offset; if (p == ®dummy) return; // Find last node. scan = p; for (;;) { temp = regnext(scan); if (temp == 0) break; scan = temp; } if (OP(scan) == BACK) offset = int(scan - val); else offset = int(val - scan); *(scan + 1) = static_cast((offset >> 8) & 0377); *(scan + 2) = static_cast(offset & 0377); } /* - regoptail - regtail on operand of first argument; nop if operandless */ static void regoptail (char* p, const char* val) { // "Operandless" and "op != BRANCH" are synonymous in practice. if (p == 0 || p == ®dummy || OP(p) != BRANCH) return; regtail(OPERAND(p), val); } //////////////////////////////////////////////////////////////////////// // // find and friends // //////////////////////////////////////////////////////////////////////// /* * Global work variables for find(). */ static const char* reginput; // String-input pointer. static const char* regbol; // Beginning of input, for ^ check. static const char* *regstartp; // Pointer to startp array. static const char* *regendp; // Ditto for endp. /* * Forwards. */ static int regtry (const char*, const char* *, const char* *, const char*); static int regmatch (const char*); static int regrepeat (const char*); #ifdef DEBUG int regnarrate = 0; void regdump (); static char* regprop (); #endif bool RegularExpression::find (kwsys_stl::string const& s) { return find(s.c_str()); } // find -- Matches the regular expression to the given string. // Returns true if found, and sets start and end indexes accordingly. bool RegularExpression::find (const char* string) { register const char* s; this->searchstring = string; if (!this->program) { return false; } // Check validity of program. if (UCHARAT(this->program) != MAGIC) { //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::find(): Compiled regular expression corrupted.\n"); return 0; } // If there is a "must appear" string, look for it. if (this->regmust != 0) { s = string; while ((s = strchr(s, this->regmust[0])) != 0) { if (strncmp(s, this->regmust, this->regmlen) == 0) break; // Found it. s++; } if (s == 0) // Not present. return (0); } // Mark beginning of line for ^ . regbol = string; // Simplest case: anchored match need be tried only once. if (this->reganch) return (regtry(string, this->startp, this->endp, this->program) != 0); // Messy cases: unanchored match. s = string; if (this->regstart != '\0') // We know what char it must start with. while ((s = strchr(s, this->regstart)) != 0) { if (regtry(s, this->startp, this->endp, this->program)) return (1); s++; } else // We don't -- general case. do { if (regtry(s, this->startp, this->endp, this->program)) return (1); } while (*s++ != '\0'); // Failure. return (0); } /* - regtry - try match at specific point 0 failure, 1 success */ static int regtry (const char* string, const char* *start, const char* *end, const char* prog) { register int i; register const char* *sp1; register const char* *ep; reginput = string; regstartp = start; regendp = end; sp1 = start; ep = end; for (i = RegularExpression::NSUBEXP; i > 0; i--) { *sp1++ = 0; *ep++ = 0; } if (regmatch(prog + 1)) { start[0] = string; end[0] = reginput; return (1); } else return (0); } /* - regmatch - main matching routine * * Conceptually the strategy is simple: check to see whether the current * node matches, call self recursively to see whether the rest matches, * and then act accordingly. In practice we make some effort to avoid * recursion, in particular by going through "ordinary" nodes (that don't * need to know whether the rest of the match failed) by a loop instead of * by recursion. * 0 failure, 1 success */ static int regmatch (const char* prog) { register const char* scan; // Current node. const char* next; // Next node. scan = prog; while (scan != 0) { next = regnext(scan); switch (OP(scan)) { case BOL: if (reginput != regbol) return (0); break; case EOL: if (*reginput != '\0') return (0); break; case ANY: if (*reginput == '\0') return (0); reginput++; break; case EXACTLY:{ register int len; register const char* opnd; opnd = OPERAND(scan); // Inline the first character, for speed. if (*opnd != *reginput) return (0); len = int(strlen(opnd)); if (len > 1 && strncmp(opnd, reginput, len) != 0) return (0); reginput += len; } break; case ANYOF: if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == 0) return (0); reginput++; break; case ANYBUT: if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != 0) return (0); reginput++; break; case NOTHING: break; case BACK: break; case OPEN + 1: case OPEN + 2: case OPEN + 3: case OPEN + 4: case OPEN + 5: case OPEN + 6: case OPEN + 7: case OPEN + 8: case OPEN + 9:{ register int no; register const char* save; no = OP(scan) - OPEN; save = reginput; if (regmatch(next)) { // // Don't set startp if some later invocation of the // same parentheses already has. // if (regstartp[no] == 0) regstartp[no] = save; return (1); } else return (0); } // break; case CLOSE + 1: case CLOSE + 2: case CLOSE + 3: case CLOSE + 4: case CLOSE + 5: case CLOSE + 6: case CLOSE + 7: case CLOSE + 8: case CLOSE + 9:{ register int no; register const char* save; no = OP(scan) - CLOSE; save = reginput; if (regmatch(next)) { // // Don't set endp if some later invocation of the // same parentheses already has. // if (regendp[no] == 0) regendp[no] = save; return (1); } else return (0); } // break; case BRANCH:{ register const char* save; if (OP(next) != BRANCH) // No choice. next = OPERAND(scan); // Avoid recursion. else { do { save = reginput; if (regmatch(OPERAND(scan))) return (1); reginput = save; scan = regnext(scan); } while (scan != 0 && OP(scan) == BRANCH); return (0); // NOTREACHED } } break; case STAR: case PLUS:{ register char nextch; register int no; register const char* save; register int min_no; // // Lookahead to avoid useless match attempts when we know // what character comes next. // nextch = '\0'; if (OP(next) == EXACTLY) nextch = *OPERAND(next); min_no = (OP(scan) == STAR) ? 0 : 1; save = reginput; no = regrepeat(OPERAND(scan)); while (no >= min_no) { // If it could work, try it. if (nextch == '\0' || *reginput == nextch) if (regmatch(next)) return (1); // Couldn't or didn't -- back up. no--; reginput = save + no; } return (0); } // break; case END: return (1); // Success! default: //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::find(): Internal error -- memory corrupted.\n"); return 0; } scan = next; } // // We get here only if there's trouble -- normally "case END" is the // terminating point. // //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("RegularExpression::find(): Internal error -- corrupted pointers.\n"); return (0); } /* - regrepeat - repeatedly match something simple, report how many */ static int regrepeat (const char* p) { register int count = 0; register const char* scan; register const char* opnd; scan = reginput; opnd = OPERAND(p); switch (OP(p)) { case ANY: count = int(strlen(scan)); scan += count; break; case EXACTLY: while (*opnd == *scan) { count++; scan++; } break; case ANYOF: while (*scan != '\0' && strchr(opnd, *scan) != 0) { count++; scan++; } break; case ANYBUT: while (*scan != '\0' && strchr(opnd, *scan) == 0) { count++; scan++; } break; default: // Oh dear. Called inappropriately. //RAISE Error, SYM(RegularExpression), SYM(Internal_Error), printf ("cm RegularExpression::find(): Internal error.\n"); return 0; } reginput = scan; return (count); } /* - regnext - dig the "next" pointer out of a node */ static const char* regnext (register const char* p) { register int offset; if (p == ®dummy) return (0); offset = NEXT(p); if (offset == 0) return (0); if (OP(p) == BACK) return (p - offset); else return (p + offset); } static char* regnext (register char* p) { register int offset; if (p == ®dummy) return (0); offset = NEXT(p); if (offset == 0) return (0); if (OP(p) == BACK) return (p - offset); else return (p + offset); } } // namespace KWSYS_NAMESPACE